Abstract-Every year a large number of researches has occurred on image retrieval. CBIR stands for content based image retrieval i.e. images are retrieved from databases on basis of contents rather than textual references. This paper refers to various CBIR methods in medical fields. It also include certain referential points to some feature descriptors that paved way to flourish researches in this fields. . The effectiveness of content based image retrieval lies on the feature extraction method. This paper refers the CBIR methods based on the analysis of feature descriptors. There are different methods which focus on various properties like, intensity, spatio-temporal features etc.